Gigantic sperm have been found in 17-million-year-old fossilized mussel shrimp. The specimens, collected in Queensland, Australia, carry the oldest petrified sex cells on record.

Using high-intensity X-rays, scientists were able to identify the ancient sperm in one male and three female Heterocypris collaris speciesand one female Newnhamia mckenziana. While the length of the petrified sperm cannot be calculated from the specimens, modern mussel shrimp from the same class can have sperm up to ...